﻿<!DOCTYPE html>
<html>
<head>
  <title>Draggable Link Labels That Stay On Path</title>
  <!-- Copyright 1998-2020 by Northwoods Software Corporation. -->
  <meta name="description" content="TypeScript: This variation on the LinkLabelDraggingTool extension restricts link labels to stay on the link's route while the user is dragging it." />
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <script src="../assets/js/goSamples.js"></script> <!-- this is only for the GoJS Samples framework -->
</head>
<body>
  <div id="sample">
    <div id="myDiagramDiv" style="background-color: whitesmoke; border: solid 1px black; width: 100%; height: 600px"></div>
    <p>
      This sample demonstrates a custom Tool, LinkLabelOnPathDraggingTool, that allows the user to drag the label of a Link, but
      that keeps the label exactly on the path of the link. The tool is defined at <a href="LinkLabelOnPathDraggingTool.ts">LinkLabelOnPathDraggingTool.ts</a>.
    </p>
    <p>
      The label on the link can be any arbitrarily complex object.
      It is positioned by the <a>GraphObject.segmentIndex</a> and <a>GraphObject.segmentFraction</a> properties.
      The segmentIndex is set to NaN such that the whole link path acts as the segment, and the segmentFraction is set by the LinkLabelOnPathDraggingTool.
      A two-way data binding on segmentFraction automatically remembers any modified value on the link data object in the model.
    </p>
    <p>
      The tool is derived from a similar tool, <a href="LinkLabelDraggingTool.ts">LinkLabelDraggingTool.ts</a>, that allows
      the user to drag the label in any direction from the mid-point of the Link path.
    </p>
  </div>

  <script type="module" id="code">
    import * as go from "../release/go-module.js";
    import { LinkLabelOnPathDraggingTool } from './LinkLabelOnPathDraggingTool.js';

    if (window.goSamples) window.goSamples(); // init for these samples -- you don't need to call this
    const $ = go.GraphObject.make;

    const myDiagram = $(go.Diagram, 'myDiagramDiv', // the ID of the DIV HTML element
    {
        layout: $(go.ForceDirectedLayout, { defaultSpringLength: 50, defaultElectricalCharge: 50 }),
        'undoManager.isEnabled': true
    });
    // install the LinkLabelDraggingTool as a "mouse move" tool
    myDiagram.toolManager.mouseMoveTools.insertAt(0, new LinkLabelOnPathDraggingTool());
    myDiagram.nodeTemplate =
        $(go.Node, go.Panel.Auto, { locationSpot: go.Spot.Center }, $(go.Shape, {
            fill: 'orange',
            portId: '',
            fromLinkable: true,
            fromSpot: go.Spot.AllSides,
            toLinkable: true,
            toSpot: go.Spot.AllSides,
            cursor: 'pointer'
        }, new go.Binding('fill', 'color')), $(go.TextBlock, { margin: 10, font: 'bold 12pt sans-serif' }, new go.Binding('text')));
    myDiagram.linkTemplate =
        $(go.Link, {
            routing: go.Link.AvoidsNodes,
            corner: 5,
            relinkableFrom: true,
            relinkableTo: true,
            reshapable: true,
            resegmentable: true
        }, $(go.Shape), $(go.Shape, { toArrow: 'OpenTriangle' }), $(go.Panel, 'Auto',
        // mark this Panel as being a draggable label, and set default segment props
        { _isLinkLabel: true, segmentIndex: NaN, segmentFraction: .5 }, $(go.Shape, { fill: 'white' }), $(go.TextBlock, '?', { margin: 3 }, new go.Binding('text', 'color')),
        // remember any modified segment properties in the link data object
        new go.Binding('segmentIndex').makeTwoWay(), new go.Binding('segmentFraction').makeTwoWay()));
    // create a few nodes and links
    myDiagram.model = new go.GraphLinksModel([
        { key: 1, text: 'one', color: 'lightyellow' },
        { key: 2, text: 'two', color: 'brown' },
        { key: 3, text: 'three', color: 'green' },
        { key: 4, text: 'four', color: 'slateblue' },
        { key: 5, text: 'five', color: 'aquamarine' },
        { key: 6, text: 'six', color: 'lightgreen' },
        { key: 7, text: 'seven' }
    ], [
        { from: 5, to: 6, color: 'orange' },
        { from: 1, to: 2, color: 'red' },
        { from: 1, to: 3, color: 'blue' },
        { from: 1, to: 4, color: 'goldenrod' },
        { from: 2, to: 5, color: 'fuchsia' },
        { from: 3, to: 5, color: 'green' },
        { from: 4, to: 5, color: 'black' },
        { from: 6, to: 7 }
    ]);

    window.myDiagram = myDiagram; // Attach to the window for console debugging
  </script>
</body>
</html>